276 KNUT DAHL. 



salmon and trout fisheries. In some respects they offer a vvholely 

 new base far deliberations fundamental to measures calculated 

 to promote the interests of these fisheries. 



Before proceeding to a closer description and a critical re- 

 vision of my results in relation to the principles of law tending 

 to promote these fisheries, I propose in separate chapters to 

 describe some investigations of a more special nature regarding 

 the growth and other biological features in salmon and trout, 

 which also have some importance in legislation relating to the 

 species in question. 



Chapter III. 

 On emigration and growth of young salmon. 



As is well known the maturing salmon during spring and 

 summer ascend our rivers. During autumn the large ova (ca. 

 6 mm. in diameter) are deposited among gravel and sand in 

 the spawning beds. 



Spawning in the northern parts of our country, as a rule, 

 takes place in September and October. In southern rivers 

 it may be extended to November and even to the first half of 

 December. 



Reposing among the gravel and sand of the bottom partly 

 also buried in it, these eggs develop during winter and hatch 

 from the latter end of February to the last days of April, the 

 larva, about 2 cm. long bursting the egg-capsule and emerging. 

 To begin with this larva lying practically helpless on the bot- 

 tom, is nourished by the large yolksack. After the lapse of 

 about 6 weeks the young fish commences taking nourishment 

 from the outer world, consisting of smaller insects, insect larvæ 

 and crustaceans. It also acquires the form and locomotory 

 faculties of the fry. 



